About the size of "text" in After Effects. Size apparent and true size.
Do you know any way to change the text size in the "source" property that is true size in px? Instead of "character box" that shows a surface size.

Forget the rectangle, it only served to make a comparison, that the text size in "px" shown in the "Character box" does not correspond to the real text size, shown by the rectangle shape that follows the true size of the text.
See the image that is the nominal size of the text is "70 px" and the "shape comparator" shows that the text size in height is "52.7 px". I want a way to edit this precise value, not the nominal size, surface, text on "Character box", and yes, the actual size, true, the "the source text", which appears in this comparison. It can be through an expression or another way.

Gave to see (by comparison made with shape with the expression "sourceRectAtTime ()" in size property) that this value can be acquired from some source, and edited from somewhere.But I want to know where and how?

[Tiago Cav]"Forget the rectangle, it only served to make a comparison, that the text size in "px" shown in the "Character box" does not correspond to the real text size, shown by the rectangle shape that follows the true size of the text."

Please see my post below, this number is not meant to correspond to the size of your text.

[Tiago Cav]"See the image that is the nominal size of the text is "70 px" and the "shape comparator" shows that the text size in height is "52.7 px". I want a way to edit this precise value, not the nominal size, surface, text on "Character box", and yes, the actual size, true, the "the source text", which appears in this comparison. It can be through an expression or another way."

In this specific case, assuming all capital letters are equal height and you will never exceed a single line, you can use the value from sourceRectAtTime() to drive an expression in scale:

This gets a little geeky, but the character size measures an em [link]. This is usually the distance from the highest ascender down the lowest descender; it's somewhat arbitrary and not strictly related to the cap height or x-height.

Given how consistent your typeface is, you could measure the height and figure out the ratio needed to relate the nominal size of the type with the cap height.

New in Ae CC 2014 13.2, you can also directly access the height of a text layer like this: